The effect of 14 days' intake of mounting quantities of fats and energy on a constant optimum utilizable amount of dietary protein was studied in weaned rats weighing 60 g. Growth (PER, NPR) and utilization (NPU--body, LPU--liver) parameters of biological protein value were determined, supplemented by a study of the course of the antithetical processes of gluconeogenesis and glycolysis, of the pentose cycle, the citric acid cycle and of transamination processes in the animals' liver. According to the maximum PER, NPR, NPU and LPU values, a 14 days' intake of 59.2 g fats and 4.518 MJ, corresponding to a diet containing 10% protein, 30% fat and 2.274 MJ, had the best effect on the optimum utilizable amount of casein (21 g/14 days). A diet containing 35% and 40% fat stimulated gluconeogenesis, followed by a transamination process and inhibition of glycolysis, the citric acid cycle and lipogenesis (depression of pentose cycle activity and a decrease in the amount of body fat), and simultaneously reduced the values of all four parameters of protein biological value. The results demonstrate that very best diet for newly weaned rats is one containing 10% high quality protein, 30% fat and 2.274 MJ.

• MeSH
• dietní proteiny metabolismus   MeSH
• dietní sacharidy metabolismus   MeSH
• dietní tuky metabolismus   MeSH
• energetický metabolismus * MeSH
• energetický příjem MeSH
• glukoneogeneze MeSH
• glykolýza MeSH
• játra metabolismus   MeSH
• krysa rodu Rattus MeSH
• tělesná hmotnost MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• dietní proteiny MeSH
• dietní sacharidy MeSH
• dietní tuky MeSH

In a 14-day experiment, weaned and adult rats were given ad libitum isocaloric diets with a mounting casein content (5, 10, 15, 25 and 40% by weight) and growth parameters of protein biological value, PER and NPR, and the utilization parameters NPU (body protein) and LPU (liver protein) were determined together with phosphoenolpyruvate carboxykinase (gluconeogenetic enzyme) and pyruvate kinase (glycolytic enzyme) activity in the animals' liver. The decrease in all the biological value parameters in weaned rats on 25% and 40% casein diets and in adult rats on 15%, 25% and 40% casein diets shows that these concentrations are too high for the organism. The decrease in PER and diminished weight and body and liver nitrogen increments in both age groups in animals with a low protein intake is evidence that 5% casein is an inadequate concentration. The optimum diet for weaned rats is thus a 15% casein diet and for adult rats a 10% casein diet, as confirmed by the linear correlation between weight increments, body and liver nitrogen and protein intake and also by gluconeogenetic enzyme activity. Under the given experimental conditions the study is a contribution to the determination of optimum physiological doses of proteins.

• MeSH
• dietní proteiny aplikace a dávkování   metabolismus   MeSH
• dusík metabolismus   MeSH
• fosfoenolpyruvát metabolismus   MeSH
• fosfoenolpyruvátkarboxylasa metabolismus   MeSH
• glukoneogeneze MeSH
• játra enzymologie   metabolismus   MeSH
• kaseiny aplikace a dávkování   MeSH
• krysa rodu Rattus MeSH
• odstavení MeSH
• tělesná hmotnost MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• dietní proteiny MeSH
• dusík MeSH
• fosfoenolpyruvát MeSH
• fosfoenolpyruvátkarboxylasa MeSH
• kaseiny MeSH

Male Wistar rats aged 30, 90, 150 and 360 days were fed ad libitum on diets with an optimum protein and fat content for their respective ages and an increasing saccharide content. Net protein utilization (NPU) was determined from the body nitrogen and protein intake values and the course of gluconeogenesis in the liver was measured by specific phosphoenolpyruvate carboxykinase (PEPCK) activity. According to the growth curve for the standard diet, animals aged 30 and 90 days have a high growth rate (3.245 g/day), 150-day-old rats grow more slowly (1.856 g/day) and 360-day-old animals put on scarcely any weight at all (277 mg/day). In 30-day-old rats, NPU attains maximum values in the presence of a 36% saccharide content in the diet, in 3- and 5-month-old animals in the presence of 51% saccharides and in one-year-old animals in the presence of 41% saccharides in their food. The course of gluconeogenesis also corresponds to these values. PEPCK activity in the youngest age group is greatest in the presence of 31% saccharides in the food, at 90 days it is stimulated in the presence of 31-46% saccharides, at 150 days the decisive concentration is 41 and 46% and at one year proteins are used for saccharide synthesis in diet with a 31 and 36% saccharide concentration. For optimum saccharide values, PEPCK activity is reduced in every age group; together with the maximum NPU values, this indicates that proteins are used for growth and building of the organism at an early age and for the renewal of tissues and organs and maintenance of the organism in adulthood.

• MeSH
• dietní proteiny aplikace a dávkování   metabolismus   MeSH
• dietní sacharidy aplikace a dávkování   MeSH
• dietní tuky aplikace a dávkování   MeSH
• fosfoenolpyruvátkarboxykinasa (závislá na GTP) analýza   MeSH
• glukoneogeneze MeSH
• hmotnostní přírůstek MeSH
• inbrední kmeny potkanů MeSH
• játra enzymologie   metabolismus   MeSH
• krysa rodu Rattus MeSH
• regresní analýza MeSH
• věkové faktory MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• dietní proteiny MeSH
• dietní sacharidy MeSH
• dietní tuky MeSH
• fosfoenolpyruvátkarboxykinasa (závislá na GTP) MeSH

From an age of 30 days to 150 days, male rats were given ad libitum feed with a physiological content of nutrients (adequate to their age) and with different sources of fat: sunflower oil, pork lard, butter. The net protein ratio (NPR), body fat content, and the specific activity of phosphoenolpyruvate carboxykinase PEPCK were determined every 15 days. For all the three fat sources, NPR had the same high values in the intensive growth period (age 45 and 60 days: increased protein demand for building the organism); lower and the same again are the NPR values at an age of 75 to 105 days. From an age of 120 days to 150 days (the end of maturation), the long-continued intake of lard and butter had an adverse effect on the availability of protein for the animals, though their food had a physiological structure and an optimum proportion of the saccharide components. The result correlates with the growth of PEPCK activity, as indicated by exploitation of protein as substrate for gluconeogenesis, not for proteosynthesis. Pork lard and butter with a 3.5 - to 5-fold prevalence of saturated fatty acids, compared with sunflower oil, implies that short-chain fatty acids were provided as effectors of gluconeogenesis and that, under the conditions of physiological intake of nutrients, substrates were also provided for mitochondrial synthesis of fatty acids.(ABSTRACT TRUNCATED AT 250 WORDS)

• MeSH
• dietní tuky aplikace a dávkování   MeSH
• inbrední kmeny potkanů MeSH
• krysa rodu Rattus MeSH
• proteiny metabolismus   MeSH
• stárnutí metabolismus   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• anglický abstrakt MeSH
• časopisecké články MeSH
• Názvy látek
• dietní tuky MeSH
• proteiny MeSH

In a 14-day experiment, adult rats weighting 250-260 g were given ad libitum diets with a constant protein content [casein - 10 %] and a mounting fat content [margarine - 0, 10, 20, 30 and 40 % - added at the expense of carbohydrates]. The growth parameters of protein biological value - PER and NPR - were determined and together with weight increments in correlation to protein an fat intake [a linear correlation] they were used on the basis of their regression equations to calculate the reciprocal relationships of fat and protein intake [for equality y]. By substituting the optimum protein intake [43.3 g/14 days - according to NPU], the optimum fat intake for adult rats was found to correspond to dietary fat concentrations of 9.72 % [y = weight increments], 12,82 % [y = PER] and 11.83 % [y = NPR]. These results wee verified in a biological experiment in which adult animals, for 14 days, were given a limited amount [31 g/animal per day] of diets containing 10 % protein [casein] an d9, 10, 11, 12, and 13 % fat [margarine - at the expense of carbohydrates] with the aim of studying the effect of a mounting fat intake on optimum protein intake [43.4 g/14 days]. The correctness of the mathematical method for determining the optimum fat intake was verified by a biological method [the optimum net protein utilization , NPU, which is highest in diets containing 11 % fats, i.e. 22.5 % of the total energy value of the diet]. It was also found that this method, both along and in conjunction with other methods [especially the one using the NPR parameter], was suitable for the determination of optimum nutrient values.

• MeSH
• dietní proteiny aplikace a dávkování   metabolismus   MeSH
• dietní sacharidy aplikace a dávkování   MeSH
• dietní tuky aplikace a dávkování   MeSH
• dusík metabolismus   MeSH
• fyziologie výživy * MeSH
• krysa rodu Rattus MeSH
• nutriční nároky * MeSH
• tělesná hmotnost MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• dietní proteiny MeSH
• dietní sacharidy MeSH
• dietní tuky MeSH
• dusík MeSH

In the conditions of physiological nutrient content and variable amino-acid mixtures made of casein K, gluten G and KG combination (1:1, standard diet), the 10-week effect of amino acids (until the age of 105 days, end of maturation stage) was investigated in growing rats with respect to protein utilization (net protein ratio) and to the values of lipid parameters at the end of the experiment (cholesterol, triacylglycerols, atherogenic indexes, cholesterol distribution into lipoprotein classes). A significant decrease in NPR for gluten, an insignificant decrease for casein in the growth period are related to the amino acid score of limiting amino acids--they determine rate of proteosynthesis and potential biological value--amount percentage of amino acids of the given diet for plastic processes of proteins (AS for KG 69, for K 67, for G 28; BHp for KG 83.1, for K 70.0, for G 54.1). Since day 105 amino acid utilization is balanced in all groups, hence it does not depend upon the quality of aminograms (lower rate of proteosynthesis in comparison with the growth period, for which the values of limiting amino acids are sufficiently high). Significantly decreased values of cholesterolemia and triacylglycerolemia for gluten food, insignificantly higher values for casein food, are in direct correlations with the values of Lys/Arg, Met/Arg, Met, Lys, and in indirect correlations with Arg and Arg+Glu+Gly. Distribution of HDL-cholesterol as a cholesterol percentage in HD lipoproteins is higher by 8.7% for gluten and all atherogenic indexes are significantly decreased in contrast to casein food, in which a slight decrease in HDL-cholesterol and insignificantly higher atherogenic indexes were recorded.

• MeSH
• aminokyseliny aplikace a dávkování   metabolismus   MeSH
• cholesterol analýza   MeSH
• gluteny aplikace a dávkování   MeSH
• kaseiny aplikace a dávkování   MeSH
• krysa rodu Rattus MeSH
• lipoproteiny chemie   MeSH
• potkani Wistar MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• anglický abstrakt MeSH
• časopisecké články MeSH
• Názvy látek
• aminokyseliny MeSH
• cholesterol MeSH
• gluteny MeSH
• kaseiny MeSH
• lipoproteiny MeSH

In our project, ghrelin analogs possessing enhanced stability and potential to significantly increase food intake were used. Three newly synthesized ghrelin analogs with fatty acid residues consisting of 8, 10, and 14 carbon atoms were studied. The main goal of this work was to develop a suitable analytical method for the determination of the stability of the novel ghrelin analogs in plasma. An appropriate liquid chromatography-mass spectrometry method was developed and optimized. The results obtained were compared with the data measured by using a commercial enzyme-linked immunosorbent assay kit, and a good correlation was found. A preparation strategy for plasma samples was optimized and consisted of simple dilution of the plasma samples followed by direct injection onto a very short monolithic column in combination with mass spectrometric detection. The developed analytical method was utilized for the determination of the stability of the prepared lipopeptides in plasma and for the quantification of the lipopeptides in a preliminary pharmacokinetic study. The feasibility of the developed separation method was clearly demonstrated. Accuracy and precision were within 80-120% and ±20% limits, respectively. Calibration curves were constructed in the range of 1-250 μg/mL.

• Klíčová slova
• enzyme-linked immunosorbent assay, ghrelin, lipopeptides, liquid chromatography mass spectrometry, monolithic columns,
• MeSH
• chromatografie kapalinová * MeSH
• ghrelin analogy a deriváty   MeSH
• kalibrace MeSH
• lipopeptidy krev   MeSH
• reprodukovatelnost výsledků MeSH
• tandemová hmotnostní spektrometrie * MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• ghrelin MeSH
• lipopeptidy MeSH